The present disclosure relates to subject matter contained in Japanese Patent Application P2000-205173 filed on Jul. 6, 2000, which is expressly incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a backlighted liquid crystal display (LCD) assembly mounted on a circuit substrate.
2. Description of the Related Art
LCD""s are widely used in applications where space and weight are limiting factors. One of such applications is information indicators used in compact electronic cameras, which provide visual information about various settings and conditions of a camera to, the camera user. Other compact, portable, electronic devices, such as mobile computers and cellular phones, may also often have an information display using an LCD. Because LCD""s are not self-illuminating, some sort of backlighting is desirable in order for LCD""s to be viewed even when electronic cameras or other portable electronic devices are used under night or other low light level conditions.
Light-emitting panels, such as electroluminescent (EL) panels, have been used for providing backlighting of LCD""s because an EL panel can be formed as very thin panel so that it allows backlighted LCD""s to have a highly reduced thickness. More specifically, a typical backlighted LCD assembly that is designed to be mounted on a circuit substrate includes an LCD screen panel formed as a thin, flat panel and an EL panel also formed as a thin, flat panel and disposed behind the LCD screen panel. The EL panel is disposed behind the LCD screen panel in order to provide backlighting of the LCD screen, and both of the panels are mounted on and electrically connected to the circuit substrate.
Generally, the space available for installation of a backlighted LCD assembly in an electronic camera or other portable electronic device is so limited that the assembly should be designed to have as reduced a thickness as possible. However, it has been often difficult to achieve a backlighted LCD with a sufficiently reduced thickness, primarily due to the required electrical connections between the circuit substrate and the LCD screen panel and between the circuit substrate and the EL panel. These electrical connections tend to increase the total thickness of the assembly. Further, these electrical connections may often lead to relatively high manufacturing costs of the assembly.
In view of the foregoing, it is an object of the present invention to provide a backlighted liquid crystal display assembly mounted on a circuit substrate, which includes a liquid crystal display (LCD) screen panel formed as a thin, flat panel and a light-emitting panel also formed as a thin, flat panel and providing backlighting of the LCD screen panel, wherein the required electrical connections between the circuit substrate and the LCD screen panel and between the circuit substrate and the light-emitting panel are improved in order to minimize the thickness of the assembly and/or reduce the manufacturing costs of the assembly.
In accordance with the present invention, there is provided a backlighted liquid crystal display assembly mounted on a circuit substrate. The circuit substrate has a mounting surface having contact pads formed thereon for electrical connection with the assembly. The assembly comprises: a liquid crystal display (LCD) screen panel formed as a thin, flat panel and having contact pads for external electrical connection; a light-emitting panel for providing backlighting of the LCD screen panel, the light-emitting panel being formed as a thin, flat panel and having contact pads for external electrical connection; at least one electrical-interconnection rubber member having a plurality of conductive areas formed of a conductive rubber material and at least one insulating area formed of an insulating rubber material and separating the plurality of conductive areas from each other; and a retainer structure which retains the LCD screen panel, the light-emitting panel and the at least one electrical-interconnection rubber member to the mounting surface of the circuit substrate while keeping them in a predefined positional relationship such that (i) the electrical-interconnection rubber member has a first portion disposed and compressed between the LCD screen panel and the mounting surface of the circuit substrate and a second portion disposed and compressed between the LCD screen panel and the light-emitting panel and (ii) the conductive areas of the electrical-interconnection rubber member are in contact with and provide electrical interconnection among the contact pads of the circuit substrate, the contact pads of the LCD screen panel and the contact pads of the light-emitting panel.
The LCD screen panel may have interconnection conductive traces formed thereon, each of which has opposite ends terminating at corresponding ones of the contact pads of the LCD screen panel. In such a case, the light-emitting panel and the circuit substrate may be electrically interconnected through the at least one electrical-interconnection rubber member and the interconnection conductive traces.
The LCD screen panel may have front and back surfaces, with the contact pads of the LCD screen panel being formed on the back surface of the LCD screen panel. The light-emitting panel may have front and back surfaces, with the contact pads of the light-emitting panel being formed on the front surface of the light-emitting panel. Further, the LCD screen panel and the light-emitting panel may be retained by the retainer structure such that (i) the back surface of the LCD screen panel and the front surface of the light-emitting panel are opposed to each other, (ii) the first portion of the electrical-interconnection rubber member is disposed and compressed between the back surface of the LCD screen panel and the mounting surface of the circuit substrate and (iii) the second portion of the electrical-interconnection rubber member is disposed and compressed between the back surface of the LCD screen panel and the front surface of the light-emitting panel.
The light-emitting panel may be retained to the mounting surface of the circuit substrate, with the back surface of the light-emitting panel being pressed against the mounting surface by resilient force of the at least one electrical-interconnection rubber member being compressed.
The LCD screen panel may be generally rectangular in shape and have a first pair of opposite side edges and a second pair of opposite side edges, with the contact pads of the LCD screen panel being arranged in a pair of rows extending along the first pair of opposite side edges, respectively. The at least one electrical-interconnection rubber member may comprise first and second bar-like electrical-interconnection rubber members extending along the first pair of opposite side edges, respectively, of the LCD screen panel. Further, the first bar-like electrical-interconnection rubber member may have a first portion disposed and compressed between the LCD screen panel and the mounting surface of the circuit substrate and a second portion disposed and compressed between the LCD screen panel and the light-emitting panel.
The light-emitting panel may be generally rectangular in shape and have a first pair of opposite side edges, a second pair of opposite side edges and a tab portion projecting from one of the first pair of opposite side edges, with the contact pads of the light-emitting panel being located on the tab portion. In such a case, the second portion of the first bar-like electrically-interconnection rubber member may be disposed and compressed between the LCD screen panel and the tab portion of the light-emitting panel.
The retainer structure may comprise a generally rectangular frame for receiving therein and locating the LCD screen panel, the light-emitting panel and the first and second bar-like electrical-interconnection rubber members relative to the frame.
In addition, the retainer structure may comprise a retainer cap for (i) retaining the rectangular frame at its desired positions on the mounting surface of the circuit substrate and (ii) engaging the front surface of the LCD screen panel along the side edges thereof to press the LCD screen panel against the bar-like electrical-interconnection rubber members so as to compress the latter.